Bulverism is the logical fallacy of assuming without discussion that a person is wrong and then distracting his or her attention from this (the only real issue) by explaining how that person became so silly, usually associating it to a psychological condition. The fallacy deals with secondary questions about ideas rather than the primary one, thus avoiding the basic question or evading the issues raised by trains of reasoning. It is essentially dodging your opponent's argument by treating them like a psychiatry patient who needs your evaluation to explain why they came up with such a ridiculous argument in the first place.

The fallacy was coined by C.S. Lewis in his essay, First and Second things.